Unit 10: Biomolecules – Important Questions with Previous Year Board Questions
Note for Students: This resource provides very important questions from Unit 10: Biomolecules along with authentic previous years’ board questions (PYQs) from CBSE, Delhi, and All India exams. Use this to master important concepts and practice questions asked in real board exams.
1-Mark Questions
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Define monosaccharides. Give one example.
Simplest carbohydrates which cannot be hydrolyzed further; example: glucose.
[All India 2010] -
Name the storage polysaccharide in animals.
Glycogen.
[All India & Delhi Boards – Multiple years] -
What is a peptide bond?
Covalent –CO–NH– linkage between amino acids.
[Delhi 2009] -
Name one water-soluble and one fat-soluble vitamin.
Water-soluble: Vitamin C; Fat-soluble: Vitamin A.
[Delhi 2009] -
State one function of insulin.
Regulates blood glucose by promoting cellular uptake.
[CBSE 2020] -
Write complementary base pairs of DNA as per Chargaff’s rule.
Adenine pairs with thymine (A–T); guanine pairs with cytosine (G–C).
[Various Boards]
2-Mark Questions
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Differentiate aldoses and ketoses with example.
Aldose contains an aldehyde group (e.g., glucose); ketose contains a keto group (e.g., fructose).
[All India 2010] -
What are reducing sugars? Example among disaccharides.
Sugars that reduce Tollen’s/Fehling’s reagents; lactose and maltose are examples.
[Comp. Delhi 2012] -
Write two differences between D- and L-configuration of monosaccharides.
D form has –OH group on the right of penultimate carbon, L form on the left.
[CBSE 2021] -
Explain denaturation of proteins with example.
Loss of natural shape and function due to heat or chemicals; e.g., egg white coagulation.
[Various Boards] -
Mention one function and deficiency disease of Vitamin C.
Function: collagen synthesis, antioxidant; deficiency causes scurvy.
[Delhi 2009] -
State two differences between DNA and RNA.
DNA is double-stranded, contains thymine and deoxyribose sugar. RNA is single-stranded, contains uracil and ribose sugar.
[CBSE 2020]
3-Mark Questions
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Explain mutarotation of glucose.
Change in optical rotation due to equilibrium between α and β anomers via open-chain form.
[CBSE 2019] -
Compare starch, cellulose, and glycogen.
Starch: plant storage, α-glucose; cellulose: structural polymer, β-glucose; glycogen: animal storage, branched.
[Various Boards] -
Compare primary, secondary, tertiary structures of proteins.
Primary: amino acid sequence; secondary: α-helices/β-sheets; tertiary: 3D folding.
[Multiple Boards] -
What are hormones? Functions of thyroxine, adrenaline, insulin.
Chemical messengers;
Thyroxine regulates metabolism;
Adrenaline triggers fight/flight response;
Insulin lowers blood glucose.
[CBSE 2020, Delhi 2010] -
Functions of Vitamins A, D, and K.
A: Vision; D: Calcium metabolism; K: Blood clotting.
[CBSE 2021] -
What are nucleosides and nucleotides? Examples.
Nucleoside = base + sugar (e.g., adenosine); nucleotide = base + sugar + phosphate (e.g., ATP).
[CBSE 2014]
5-Mark Questions
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Write open chain and cyclic structures of glucose; explain two reactions confirming aldehyde group.
Open chain is aldohexose; cyclic forms are α and β pyranose.
Reactions: reduces Fehling’s/Tollen’s reagent; reacts with HCN to form oxime.
[All India 2012] -
Structures of sucrose, lactose, maltose; which are reducing sugars and why?
Sucrose is non-reducing; lactose and maltose are reducing due to free anomeric hydroxyl groups.
[CBSE 2023, Delhi 2012] -
Describe four levels of protein structure with labelled diagrams.
Primary (amino acid sequence), secondary (α-helix/β-sheet), tertiary (3D folding), quaternary (multiple polypeptides).
[Repeated boards] -
Explain Watson-Crick model of DNA with sketch; two functions of DNA in organisms.
Double helix structure with antiparallel strands and complementary base pairing (A–T and G–C).
DNA stores genetic info, acts as template for protein synthesis.
[CBSE & Various Boards]